Which of the following pairs have highest electronegativity difference?
\( \mathrm{H} \) and \( \mathrm{F} \)
\( \mathrm{Li} \) and \( \mathrm{Cl} \)
\( \mathrm{Na} \) and \( \mathrm{Cl} \)
\( \mathrm{Cs} \) and \( \mathrm{F} \)